This invention relates to the generation and/or regeneration of cyclic composite signals whose frequencies may or may not be harmonically or musically related, whose amplitudes are independent of frequency, and particularly whose frequencies may be any multiple "N" times the input frequency such that "N" is any positive real number, rational or irrational, less than, greater than or equal to unity.
In audiometery it is occasionally desirable to listen on the spot to cyclic composite signals, whose frequencies may be in the ultra-sonic or sub-sonic ranges, in their entirety and without disturbing their harmonic structure. This is particularly useful in analyzing coronary conditions, since the ear can detect a much smaller change in harmonic structure and thus in waveshape, than can an oscilloscope or an electrocardiogram.
One can record the phenomena and then play it back at a different speed but at the sacrifice of simultaneity and particularly for sub-sonic phenomena, one must record for a long interval of time and only have accumulated enough information to listen for a short time.
Also in music it is frequently desirable to produce automatically and simultaneously, several tones which are related musically and whose harmonic structures may be identical to the input signal or, selectably, entirely different. In other words, to play (or sing) harmonies to the single melody line of an instrument or vocalist.
A known system for providing composite output signals of harmonics of a signal is disclosed in U.S. Pat. No. 3,403,343, but this system requires the use of a permanent storage system for storing the amplitude values of a sine wave.